The production of thermoset polymers by the ring-opening or metathesis polymerization of polycycloolefins is well known in the art. Numerous patents and literature references, both U.S. and foreign, relate to such polymerization, particularly the polymerization of dicyclopentadiene, in the presence of a variety of olefin metathesis catalyst systems. Among the more effective ring-opening polymerization catalyst systems are homogeneous catalyst systems based on tungsten or molybdenum halides, often employed with an organotin or organoaluminum compound. One such catalyst system is disclosed by Sjardijn et al, U.S. Pat. No. 4,810,762, wherein substituted phenolic tungsten halides are used with organotin hydrides. In copending U.S. patent application Ser. No. 278,101, filed Nov. 30, 1988, there is disclosed a catalyst system which comprises phenol-treated tungsten halides including the oxyhalide combined with an organotin or organoaluminum compound which is utilized with a boron halide catalyst promoter. Bulk polymerization of dicyclopentadiene in the presence of a similar catalyst is shown by U.S. Pat. No. 4,729,976.
Catalysts containing higher proportions of phenolic moieties have been shown to metathesize some olefins. Taghizadeh et al, J. Molecular Catal., 15, 219 (1982) teach catalysts of the W(OAr).sub.6 type, wherein Ar is an aryl group, and the relatively ineffective use of such catalysts with 2-pentene and norbornene. Compounds of the type WX.sub.2 (OAr).sub.4, wherein X is halogen and Ar is aryl, have been shown to effect methathesis of acyclic olefins by Dodd et al, J. Mol. Catal. 15 103 (1982).
It is characteristic of the operation of many if not most olefin metathesis catalyst systems that the presence of reactive materials such as water and oxygen should be avoided. While small amounts of such reactive materials are acceptable, amounts of water, for example, in excess of 20 parts per million (ppm) are generally to be avoided, particularly if the catalyst system is based on tungsten. As a result, it is necessary to thoroughly dry the cycloolefinic monomers prior to contact with the polymerization catalyst and to conduct the polymerization in an inert environment, e.g., in a nitrogen or argon atmosphere.
A few olefin metathesis catalyst systems based on the relatively more exotic metals are able to effect ring-opening polymerization in the presence of water. Ruthenium-based catalysts that are water tolerant and, in fact, may even require water or other polar solvent to be effective are disclosed by Natta et al, Polym. Lett., 2 349 (1964) and by Novak et al, J. Am. Chem. Soc., 110 7542 (1988). It would be of advantage, however, to provide a tungsten-based catalyst system which would effect polycycloolefin metathesis polymerization in the presence of the water normally present in the undried polycycloolefin monomers.